docs(batches): update limitations for github apps (#604)

Better structure of of limitations

Author: bahrmichael

docs/batch-changes/configuring-credentials.mdx

@@ -194,12 +194,12 @@ When Sourcegraph is configured to [clone repositories using SSH via the `gitURLT
 
 EXPERIMENTAL: Using GitHub Apps to authenticate Batch Changes is currently experimental, and there may still be some rough edges.
 
-Features currently not supported are
-- running a batch change with `fork: true` that targets a public repository on github.com
+GitHub apps follow the same concepts as [personal and global access tokens](#types-of-access-tokens-used-by-batch-changes).
 
-This is only available for GitHub code hosts.
+### Limitations
 
-GitHub apps follow the same concepts as [personal and global access tokens](#types-of-access-tokens-used-by-batch-changes).
+- GitHub apps can only be used with GitHub code hosts.
+- The forking mechanism (`fork:true`) is only supported if the GitHub app has access to all repositories of the installation, and if the origin repository and the fork are in the same organization that the GitHub app is installed to ([GitHub Docs](https://docs.github.com/en/rest/repos/forks?apiVersion=2022-11-28#create-a-fork)).
 
 ### Adding a GitHub app